My worst enemy is the office snack

Over the past six months I have come up against many fearsome enemies in my quest to lose weight. I have faced down the allure of roast dinners. I have taken on bad street design to become a walking machine. I have encountered the sheer, unbridled ropiness that is the fitness video market, and, while I have not found a way to combat this, I have not been bowed either, and have simply avoided it as I would a wheatgrass shake or anything involving spirulina. But I have finally realised that there is an enemy that cannot be vanquished. An enemy that has the power to prise your resolutions from you, spit on them, cast them to the ground in curled-lip disgust, before looking you up and down, laughing and hissing: "Still beefy, aren't you?"

That enemy is the office snack.

I've certainly snacked while working before. As a housebound freelancer in my mid-20s, I padded to the kitchen approximately once an hour to prise open the fridge and stare in expectantly, in the hope that said appliance had somehow worked out how to grow food since my last visit. Perhaps there was actually a splendid harvest festival hidden behind the last mouldy bit of Boursin, and my earlier excavations simply hadn't been meticulous enough.

On coming to the Guardian two years ago, those fridge-diving days came to an end. Most of the time I sit at a bank of desks that is peopled by extremely friendly colleagues, but not well organised for food sharing - the piles of books, magazines and CDs that have sprung up around us are too unstable to support a communal box of biscuits.

Three weeks ago, though, I moved desk to an area where the food-sharing logistics are perfect. A place where boxes of cookies have space to breathe; where a huge, shared bag of crisps can spread out and sigh like an exhibitionist on the beach. And finding myself sitting in the middle position among these desks, I also realised that there was a long-established spot for these shared office snacks: right beneath my nose.

What treats could be found there. The gorgeous chocolate brownies that one colleague whipped up in the kitchen. The brilliantly fragrant biscuits that another brought back from a holiday in Iran. The fabulous home-made biscuits that another made with his toddler son. I repeat: his toddler son. To resist would have been rude.

The stakes rose higher as a chocolatier started sending me small daily samples of their wares. Now, I know that occasional freebies are an enviable perk of being a journalist, and I also know how many people would be delighted by a daily chocolate delivery, but this started to make me feel anxious. It was fine when it was just a chocolate bar each morning - I could hand this straight to my neighbour and everyone would make quick work of it. But when said chocolatier sent in a sack of treats - milk chocolate, dark chocolate, chilli chocolate; boxes full of strawberry creams, caramels and mint surprises - I was in trouble. For the next week, each day veered off in one of two directions. Either I succumbed to the snacks by mid-morning and spent the entire day chowing. Or I would somehow hold off until I arrived home, before heading straight for the fridge, to find that there was indeed a harvest festival hidden behind the cheese, and that it was cantering towards my gullet.

I started thinking counterintuitively. Maybe if I added to the snack orgy by buying a tub of muffins, I could fatten everyone else up, and start looking and feeling thinner by default. It was a brilliant plan! Genius! A triumph!

I bought the muffins. I ate the muffins.

Suffice to say it has been a harrowing few weeks, and my belly now looks as though it is harbouring an unhappy family of kangaroos. Still, while the office snack is victorious in its wrapper-strewn kingdom, I am fleeing its tyranny and running straight into the arms of another dieting enemy. I love holiday food, I really do, but gosh darn, don't it make you fat?